The field of the invention is systems and methods for medical image reconstruction. More particularly, the invention relates to systems and method for simultaneously reducing image artifacts while reconstructing images from data obtained with a medical imaging system, such as an x-ray computed tomography system, where those images depict a temporal contrast dynamic, such as contrast agent uptake or dynamic physiological motion.
Time-resolved imaging methods can provide important diagnostic information related to diseases. For example, in contrast-enhanced breast imaging, the contrast uptake curve can be used as a biomarker for differentiating a benign tumor from a malignant tumor. Although cone beam computed tomography (“CBCT”) breast imaging methods have obtained FDA clearance, these methods are not without their drawbacks, including relatively high radiation dose and sensitivity to subject motion. Currently, to obtain a time-resolved CBCT image sequence, at least 4-10 CBCT acquisitions are needed. This means that radiation dose to the subject will be repeated 4-10 times and the likelihood to get images contaminated by respiratory motion is 4-10 times higher. Thus, there remains a need to provide time-resolved CBCT imaging of the breast with reduced dose and less sensitivity to motion artifacts.
Another example of time-resolved imaging is in neuro-interventional procedures. In these procedures it is common for the clinician to routinely perform a three dimensional x-ray digital subtracted angiography (“3D-DSA”) to evaluate the success of a procedure. Currently, 3D-DSA is implemented using two 3D CBCT acquisitions: one performed before contrast injection and the other acquired after contrast injection. A pre-contrast and post-contrast image are then individually reconstructed and subtracted to generated the 3D-DSA images. Again, current practices suffer from two limitations: relatively high radiation dose caused by needing two separate acquisitions and motion artifacts caused by subject motion between the two acquisitions.
Another example of time-resolved imaging is in cardiac CT imaging. With the current development of whole heart coverage detectors, it has been said the single heart beat and submillisecond acquisitions will be sufficient to freeze cardiac motion within certain heart rates. When heart rate increases, however, cardiac CT image quality suffers. Thus, there remains a need to provide time-resolved cardiac CT imaging from a single short scan acquisition.